2-Hydroxymethylenecyclohexanones

ABSTRACT

Processes and compositions for improving, modifying or enhancing the organoleptic properties of a tobacco product which comprises adding thereto an effective amount of a 2-hydroxymethylenecyclohexanone.

This is a division of application Ser. No. 927,800 filed July 25, 1978,now U.S. Pat. No. 4,183,363.

BACKGROUND OF THE INVENTION

Manufacturers of tobacco products expend a considerable effort toprovide to the consumer a product which is uniform and which has apleasant and distinctive flavor and aroma both before and duringsmoking.

The characteristic aroma and flavor were traditionally obtained byblending domestic oriental and turkish tobaccos, each of whichcontributes its own particular characteristics and nuances to the finalblend. The supply of the particular tobaccos needed to supply thesecharacteristic nuances is, however, often subject to the vagaries commonto agricultural products such as poor crop years, price instability,political turmoil etc. The popularity of filter cigarettes presentadditional problems inasmuch as certain aromatic substances may be lostwithin the filter.

In order to alleviate the impact of such problems there have beendeveloped a number of tobacco flavor additives to enhance, improve ormodify the organoleptic properties of the tobacco blends. Such additivesare used both to restore desirable characteristics of flavor, aroma andsmoke that may be lacking for one reason or another, or to provide adistinctive note to the product. A number of additives used in the artare discussed by Sidney Gutcho in Tobacco Flavoring Substances andMethods, Noyes Data Corporation, Park Ridge, N.J. (1972).

THE INVENTION

It has been found that the organoloptic properties of tobacco productscan be improved by adding thereto a 2-hydroxymethlenecclohexanone.

The addition of a 2-hydroxymethylenecyclohexanones to a blended tobaccoimproves both the aroma of the fresh tobacco and the aroma and taste ofthe blend during smoking. A comparison aroma of the treated tobacco withthe untreated tobacco shows that the blends containing2-hydroxymethylenecyclohexanones of this invention are enhanced, morerounded and mellow than the untreated tobaccos.

The differences between the treated and untreated tobaccos is even morestriking upon smoking. The untreated cigarettes have an undesirableharshness upon smoking, an effect which is diminished by adding a2-hydroxymethylenecyclohexanone according to this invention. The treatedcigarettes provide, upon smoking, a smoother, mellower, more roundedtaste which makes them much preferred over the untreated cigarettes.

The hydroxymethylene compounds of this invention were prepared from thecorresponding ketone via a base catalyzed reaction with a formate suchas ethyl formate, e.g. ##STR1## The formyl group appears to existexclusively as the hydroxymethylene tautomer, a hydrogen bond existingbetween the hydroxyl hydrogen and the carbonyl oxygen.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The 2-hydroxymethylenecyclohexanone derivatives employed in thisinvention may be represented by the general formula: ##STR2## wherein:

R₁ is chosen from the group consisting of hydrogen, methyl, ethyl,propyl, allyl and butyl;

R₂, R₃, R₄, R₅ and R₆ are chosen from the group consisting of hydrogen,methyl and ethyl; and the total number of carbons in R₁ +R₂ +R₃ +R₄ +R₅+R₆ does not exceed five.

When one of the 2-hydroxymethylenecyclohexanone derivatives of thisinvention is added to a tobacco blend, the smoking characteristics ofthat blend show a marked improvement. The harshness of the tasteexperienced upon smoking the untreated blend is greatly diminished.

Preferred among the compounds of structure I are those wherein R₂, R₃,R₄, R₅ and R₆ are either hydrogen or methyl, and the sum of the numberof carbons in the substituents (R₁ through R₆) does not exceed four. Itis interesting to note that while a number of analogs encompassed withinthis group provide the enhanced smoking characteristics when added to atobacco blend (e.g. 6-hydroxymethylene-2-methyl-2-propylcyclohexanone,2-allyl-6-hydroxymethylene-2-methylcyclohexanone,6-sec-butyl-2-hydroxymethylenecyclohexanone), compounds of similarstructure not included in the group such as4-t-butyl-2-hydroxymethylenecyclohexanone and2-hydroxymethylene-4-isopropylcyclohexanone do not, surprisingly,provide these desirable characteristics.

Even more highly preferred are those compounds of structure I whereinthe substituents R₁ through R₆ are either hydrogen or methyl and thetotal number of methyl groups does not exceed three. The members of thisgroup (e.g. 2-hydroxymethylenecyclohexanone,2-hydroxymethylene-6-methylcyclohexanone,2,3-dimethyl-6-hydroxymethylenecyclohexanone,2-hydroxymethylene-4,4,6-trimethylcyclohexanone, etc.) were particularlyeffective in reducing harshness and providing a smoother, mellower morerounded taste on smoking.

Surprisingly, closely related compounds such as3,6-dimethyl-6-hydroxymethylenecyclohexanone and2-hydroxymethylene-3,5,5-trimethylcyclohexanone do not enhance thetobacco flavor in the same manner as do the compounds of Structure I.

The amount of 2-hydroxymethylenecyclohexanone derivative to be added maydepend on several factors including the effect desired, the nature andamount of other additives used in conjunction with it and/or thepersonal preferances of the flavorist. Amounts as low as 0.01 ppm, basedon tobacco weight have been found to be effective and amounts as high as1000 ppm have been found to be usable. It is preferred, however, to useamounts in the range of 0.1 ppm to 100 ppm, with 1 ppm to 10 ppm beingespecially preferred.

It is understood that the levels suggested above are merely suggestiveof the preferred amounts and that they are always subject to the skillof the flavorist and the effect he seeks to achieve.

The additive can be added to the tobacco (cigarette paper, etc.) andblended therein by a variety of methods known in the art.

ILLUSTRATION OF THE PREFERRED EMBODIMENTS

The following examples are included to illustrate the preferredembodiments of this invention and should not be construed as limiting.They are intended to embrace any equivalents or obvious extensions whichare known or should be known to persons skilled in the art.

EXAMPLE I

The following example illustrates a method for preparing the2-hydroxymethylenecyclohexanone derivatives.

A. 2-Hydroxymethylenecyclohexanone

Cyclohexanone (200 grams, 2.0 moles) is added dropwise over a period of2.75 hours to a stirred mixture of sodium hydride (50% oil dispersion,105 grams, 2.1 moles), ethyl formate (200 grams, 2.7 moles), anhydrousethanol (5 ml) and hexane (3500 ml) at 20° C. under nitrogen. Stirringis continued at room temperature for an additional 20 hours at whichtime a quantity of water sufficient to dissolve the reaction mixture isadded. The layers are separated and the organic phase is washed twicewith 5% aqueous sodium hydroxide. The combined aqueous phases areacidified with 25% aqueous sulfuric acid, and extracted three times withhexane. The organic phase is then washed twice with water, and distilledthrough a 4" vigreaux column at a 1:1 reflux take off ratio from 1 ghydroquinone to yield 318 g (63% theory)2-hydroxymethylenecyclohexanone.Bp 47°-48° C. @ 0.5 mm.

The above procedure is similar to that reported in Organic Synthesis,Coll. Vol. 4, John Wiley and Sons, Inc., New York, 1963, pp. 536.

A number of higher analogs of 2-hydroxymethylenecyclohexanone wereprepared in a similar manner from the appropriate ketones. These arelisted in Table I, following Example II.

EXAMPLE II

This example illustrates the advantages of adding the2-hydroxymethylenecyclohexanone compounds to a cigarette.

Cigarettes were prepared from a tobacco blend described below.

    ______________________________________                                        Tobacco Used   Parts by Weight                                                ______________________________________                                        Bright         60                                                             Burley         20                                                             Oriental       10                                                             Bright Stems   10                                                                            100                                                            ______________________________________                                    

Half of the cigarettes, those used as controls, had no additives. Theother half of the cigarettes were treated with2-hydroxymethylenecyclohexanone. The level of the additive was about tenparts per million.

A bench panel of smokers compared the two cigarettes. They did not knowwhich of the cigarettes had been treated. The cigarettes containing the2-hydroxymethylenecyclohexanones were described as smoother, moretobacco like and of generally better quality than the controlcigarettes.

Table I lists a number of the compounds tested along with the yields(based on theory) obtained when prepared according to a process similarto Example I, their boiling points at 0.5 mm, and the effect they haveon smoking when tested as described above. Those compounds marked withan asterisk are comparative compounds and are not compounds of FormulaI.

                  TABLE I                                                         ______________________________________                                        Compound           Effect upon smoking                                        ______________________________________                                        1.  2-Hydroxymethylene-                                                                              Smoothing, mellowing,                                      cyclohexanone.     good mouth feel. Reduces                                   (63%; 47-8° C.)                                                                           harshness, enhanced tobacco                                                   flavor.                                                2.  2-Hydroxymethylene-6-methyl-                                                                     Reduces harshness, mellow-                                 cyclohexanone.     ing, enhances impact of                                    (70%; 52-3° C.)                                                                           tobacco flavor.                                        3.  2-Hydroxymethylene-5-methyl-                                                                     Mellowing, reduces harsh-                                  cyclohexanone.     ness, smoothing.                                           (70%; 58-60° C.)                                                   4.  2-Hydroxymethylene-4-methyl-                                                                     Reduces harshness and                                      cyclohexanone.     bitterness, smoothing,                                     (84%; 61-2° C.)                                                                           mellowing.                                             5.  2,3-Dimethyl-6-hydroxymethyl-                                                                    Mellowing, good delivery,                                  enecyclohexanone   smoothing, reduces harsh-                                  (90%; 53-5° C.)                                                                           ness, enhanced tobacco                                                        flavor.                                                6.  *3,6-Dimethyl-2-hydroxy-                                                                         Neutralizes smoke com-                                     methylenecyclohexanone                                                                           pletely.                                                   (74%; 63-4° C.)                                                    7.  2-Hydroxymethylene-4,4,6-                                                                        Smoother, fuller and rich-                                 trimethylcyclohexanone                                                                           er taste impact, reduces                                   (88%; 56-7° C.)                                                                           harshness.                                             8.  *2-Hydroxymethylene-3,5,5-                                                                       Off taste, dilutes smoke.                                  trimethylcyclohexanone                                                        (85%; 56-7° C.)                                                    9.  *2-Hydroxymethylene-4-iso-                                                                       Off taste, harsh.                                          propylcyclohexanone                                                           (87%; 72-3° C.)                                                    10. *4-t-Butyl-2-hydroxymethy-                                                                       No enhancement of tobacco,                                 lenecyclohexanone  flavor, not mellowing.                                     (89%; 84-5° C.)                                                    11. 6-sec-Butyl-2-hydroxy-                                                                           Smoothing, mellowing                                       methylenecyclohexanone                                                                           effect on smoke, reduces                                   (74%; 88-9° C.)                                                                           harshness.                                             12. 6-Hydroxymethylene-2-methyl                                                                      Smoothing, mellowing,                                      2-propylcyclohexanone                                                                            good fullness, reduces                                     (71%; 80-1° C.)                                                                           harshness.                                             13. 2-Allyl-6-hydroxymethylene-                                                                      Mellowed sidestream,                                       2-methylcyclohexanone                                                                            reduced harshness.                                         (77%; 68-9° C.)                                                    14. 2-Ethyl-6-hydroxymethylene-                                                                      Less harsh, more mellow.                                   2-methylcyclohexanone.                                                        (71%; 60-1° C.)                                                    ______________________________________                                         *Indicates a comparative compound.                                       

EXAMPLE III

This example illustrates the advantages of adding2-hydroxymethylenecyclohexanone compounds to a tobacco flavoringcomposition.

The following tobacco flavor compositions were prepared.

    ______________________________________                                                              Parts by Weight                                         Ingredients             A      B      C                                       ______________________________________                                        Solid extract Deertongue leaves                                                                       10     10     10                                      Water                   20     20     20                                      Alcohol                 47     37     37                                      Coumarin                5      5      5                                       Ethyl Oxyhydrate        15     15     15                                      Linalool                1      1      1                                       Δ-Decalactone     1      1      1                                       α-Ionone          1      1      1                                       2-Hydroxymethylenecyclohexanone                                                                       --     10     --                                      6-Methyl-2-hydroxymethylenecyclohexanone                                                              --     --     10                                                              100    100    100                                     ______________________________________                                    

Three groups of cigarettes were prepared and each group was treated withone of the above formulations at a level of ten parts per million.

The cigarettes were evaluated by a test panel. Those cigarettes treatedwith formula A, the formula having neither of the2-hydroxymethylenecyclohexanones of this invention, were judged to beharsh and strong.

In comparison, the cigarettes treated with formula B were consideredsmoother than A. The smoking qualities of the cigarettes were judged asenhanced when compared with A. Similarly those treated with formula Cwere described as being smoother, more rounded and more palatable thanthe cigarettes containing A.

Other compounds of formula I could be substituted for the2-hydroxymethylenecyclohexanone in the above formulations with similarresults being expected.

We claim:
 1. 2-Hydroxymethylene-4,4,6-trimethylcyclohexanone. 2.6-Hydroxymethylene-2-methyl--propylcyclohexanone. 3.2-Allyl-6-hydroxymethylene-2-methylcyclohexanone. 4.2-Ethyl-6-hydroxymethylene-2-methylcyclohexanone.